The present invention generally relates to thermal color printers, and more particularly to a thermal color printer provided with a mechanism for moving a sheet of paper on which a color image is printed.
A conventional thermal color printer generally has a thermal printing head and a platen drum on which a sheet of paper is clamped. The thermal color printer uses an ink sheet which has successive portions of n different colors to print in n colors during a time in which the platen drum undergoes n revolutions. In such a thermal color printer, a high accuracy is required of dot positions so that dot positions of corresponding dots printed by the ink of different colors coincide in order to obtain a satisfactory color image.
In order to match the dot positions of the corresponding dots for each of the colors used, it is essential that the sheet of paper clamped on the platen drum does not move. It was conventionally considered best to carry out the color printing in a state where a tip end portion of the paper is clamped on the platen drum because this method of printing was effective in reducing a skew of the paper. However, as the platen drum undergoes several revolutions, the paper inevitably moves with respect to the platen drum since only the tip end portion of the paper is clamped on the platen drum. In order to improve the quality of the printed color image, it is necessary to further improve the accuracy with which the dot positions of the corresponding dots for each of the colors used are matched but there conventionally is no thermal color printer which can meet such demands.